chore: initial import from KNEL/PFVCluster@041d311 [#769]

Split per O&M lane work order. Full history: KNEL/PFVCluster.
shellcheck debt fixed in librenms-agent (quoting, arithmetic, backticks);
fixes upstream ntp-server.sh bug: input_wakeups reported PACKETSENDFAILURES
instead of INPUTWAKEUPS. mysql.sh (PHP-in-.sh) exempt per house rule.

https://projects.knownelement.com/issues/769#note-4152

oxidized/hooks/git-push.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+# Oxidized post-push hook: auto-push to Gitea after each config change
+# Mounted into container at /home/oxidized/.config/oxidized/hooks/checkout/git-push.sh
+set -euo pipefail
+cd "$1"
+export GIT_SSH_COMMAND="ssh -o StrictHostKeyChecking=accept-new -i /home/oxidized/.config/oxidized/.ssh/id_ed25519"
+git push origin master 2>&1 || true